Top 5 Adaptations in Timing and Synchronization Enabling the IoT

Cutting edge, innovative, and exhilarating, the IoT has caught the attention of millions of businesses and consumers around the world. It’s easy to mistake the technologies of the IoT and their profitability as an overnight success; however, it would not be possible without key innovations over decades of work. At the heart of IoT technology is electronic timing. Adaptations in timing and synchronization are being pioneered to address the unique challenges that come with the IoT; these solutions are the unsung heroes that keep our data collection clean and our devices in sync. Below are the top 5 adaptations in timing and synchronization technology enabling the IoT.

1. Quartz crystals with lowest possible plating load capacitance (CL) and equivalent series resistance (ESR).

The most significant trend in IoT is conserving battery power while still boosting overall functionality. Advanced IC subsystems are continuously starved of energy, forcing them to operate with lower power consumption. The direct result of reduced power consumption is a decrease in oscillation gain margin in the Pierce oscillator with industry low gm_critical – a defining metric for strength of the oscillator circuit. gm_critical has been pushed to the lowest limits in a wide variety of IoT optimized chipsets requiring adaptations in quartz crystal technology. One significant adaptation is an ever lower CL and ESR value.

Today’s crystal has evolved to meet the lowest levels of CL combined with the lowest ESR available. Lowering both CL and ESR simultaneously leads to a crystal that is much easier to drive and is capable of being driven using a Pierce oscillator configured with a low gm_critical value. Saving the most amount of power consumption, the leading edge of crystal design is now enabling CL of 3pF or 4pF for a wide variety of frequencies. With such low CL values, designers of energy saving MCUs and RF chipsets can optimize their designs to run on lower power consumption than ever before.

2. Sub 100nA timekeeping current consumption real time clocks (RTC).

Many smart IoT devices are often deployed over a wide perimeter and are expected to operate autonomously for years without routine maintenance. For these devices, power consumption is everything. The last 50nA could mean the difference between sustained operability on a tiny coin cell or sacrificing real estate by installing a larger battery. Previous RTC technology can be up to 10X more power hungry than today's state of the art. When the RTC in the system is the only heartbeat that remains active in deep sleep, reducing the time keeping current consumption to 22nA translates into a significant extension of battery life. Sub 100nA power consumption RTC's keep IoT devices running in deep sleep for as long as necessary.

3. Micro-footprint MEMS oscillators.

Size is a considerable design challenge for the IoT and wearable device market. Although MEMS oscillators aren’t the lowest cost solutions and usually less efficient in terms of power consumption, they are the reigning kings of small form factor designs. Available in “chipscale” packages - the size of a single silicon die - MEMS oscillators offer output frequencies from 32.768kHz to >100MHz in miniature footprints as small as 1.5mm x 0.8mm. Micro-footprint MEMS oscillators are the ideal solution for miniaturized IoT devices.

4. Compact advanced TCXOs.

Femtocells, LoRa radios, machine to machine (M2M) devices, GPS tracking and other IoT systems rely heavily on accurate long term timing stability to synchronize their communications and avoid spectral and time division interference. Acquiring a GPS signal from a distant satellite, locking to the signal, and calculating it’s exact coordinates on the surface of the earth requires precise millisecond to millisecond timing. Base transceiver stations (BTS) and other cellular devices, now migrating to 5G, act on precise transmit windows. Blurring these time-based boundaries leads to higher bit error rate, violates standards and specifications and increases unnecessary noise and interference. Today's compact TCXO devices achieve ±1ppm to ±0.1ppm frequency stability over temperature, ideal for many compact RF and GPS applications that are driving the IoT.

5. < 200-fs ultra-low jitter oscillators.

Without the accessibility of the cloud and the explosive growth in bandwidth capabilities, the IoT would not exist. For instance, increasing bandwidth in servers, storage systems, and network interfaces—both short and long haul—depends directly on the continuous evolution of low noise clocks. Ultra-high speed serial rates that exceed 50 gigabits per second (Gbps) require sub-200 fs (RMS) reference clock phase jitter performance. Higher phase noise would exceed the level required for low bit error rate transmission between SERDES and RF devices. Today's generation of ultra-low noise & jitter clocks enable the exponential growth in high speed data traffic driving the cloud.